PLL lock management system
First Claim
1. An apparatus comprising:
- a voltage controlled oscillator (VCO);
a loop filter operative to provide a control voltage to lock the VCO to a desired operating frequency; and
a calibration unit operative to determine an initial control voltage for the desired operating frequency and to pre-charge the loop filter to the initial control voltage.
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Accused Products
Abstract
A PLL includes a charge pump, a loop filter, a VCO, and a calibration unit. The calibration unit performs coarse tuning to select one or multiple frequency ranges, performs fine tuning to determine an initial control voltage that puts the VCO near a desired operating frequency, measures the VCO gain at different control voltages, and derives VCO gain compensation values for the different control voltages. The calibration unit also pre-charges the loop filter to the initial control voltage to shorten acquisition time, enables the loop filter to drive the VCO to lock to the desired operating frequency, and performs VCO gain compensation during normal operation. For VCO gain compensation, the calibration unit measures the control voltage, obtains the VCO gain compensation value for the measured control voltage, and adjusts the gain of at least one circuit block (e.g., the charge pump) to account for variation in the VCO gain.
69 Citations
37 Claims
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1. An apparatus comprising:
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a voltage controlled oscillator (VCO);
a loop filter operative to provide a control voltage to lock the VCO to a desired operating frequency; and
a calibration unit operative to determine an initial control voltage for the desired operating frequency and to pre-charge the loop filter to the initial control voltage. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An integrated circuit comprising:
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a voltage controlled oscillator (VCO);
a loop filter operative to provide a control voltage to lock the VCO to a desired operating frequency; and
a calibration unit operative to determine an initial control voltage for the desired operating frequency and to pre-charge the loop filter to the initial control voltage.
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8. An apparatus comprising:
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a voltage controlled oscillator (VCO) having a plurality of frequency ranges;
a loop filter operative to provide a control voltage to lock the VCO to a desired operating frequency; and
a calibration unit operative to perform coarse tuning to select a frequency range from among the plurality of frequency ranges, to perform fine tuning to determine an initial control voltage for the desired operating frequency, and to provide the initial control voltage to the loop filter, wherein the selected frequency range covers the desired operating frequency. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of controlling an oscillator in a phase-locked loop (PLL), comprising:
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performing fine tuning to determine an initial control voltage to operate the oscillator near a desired operating frequency;
pre-charging a loop filter to the initial control voltage; and
enabling the loop filter to lock the oscillator to the desired operating frequency starting from the initial control voltage. - View Dependent Claims (23, 24, 25, 26, 27)
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28. An apparatus comprising:
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a first control unit operative to perform coarse tuning to select a frequency range from among a plurality of frequency ranges for an oscillator, the selected frequency range covering a desired operating frequency;
a second control unit operative to perform fine tuning to determine an initial control voltage for the desired operating frequency; and
a third control unit operative to pre-charge a loop filter to the initial control voltage and to enable the loop filter to lock the oscillator to the desired operating frequency starting from the initial control voltage. - View Dependent Claims (29, 30)
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31. An apparatus comprising:
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means for performing coarse tuning to select a frequency range from among a plurality of frequency ranges for an oscillator, the selected frequency range covering a desired operating frequency;
means for performing fine tuning to determine an initial control voltage for the desired operating frequency;
means for pre-charging a loop filter to the initial control voltage; and
means for enabling the loop filter to lock the oscillator to the desired operating frequency starting from the initial control voltage.
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32. An apparatus comprising:
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a voltage controlled oscillator (VCO) operative to receive a control voltage and provide an output signal at a desired operating frequency;
a converter operative to measure the control voltage applied to the VCO;
a look-up table operative to provide a VCO gain compensation value for the measured control voltage; and
at least one circuit block having an adjustable gain that is varied by the VCO gain compensation value. - View Dependent Claims (33, 34, 35)
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36. An apparatus comprising:
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means for measuring a control voltage applied to a voltage controlled oscillator (VCO) in a phase-locked loop (PLL) to lock the VCO to a desired operating frequency;
means for obtaining a VCO gain compensation value for the measured control voltage; and
means for varying an adjustable gain of at least one circuit block within the PLL based on the VCO gain compensation value. - View Dependent Claims (37)
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Specification